Originally located on Presidio Hill near Old Town, the mission moved to its present location just east of Qualcomm Stadium in 1774. Confiscated by the Mexican government in 1834, it was occupied by the U.S. Army in 1853. President Abraham Lincoln restored it to the Catholic Church in 1862. Then in ruins, the mission was gradually restored. It once again became an active church in 1941.

In 1976, Pope Paul VI designated the mission as a minor basilica, honoring its historic role.

The mission is now finishing an earthquake retrofitting project in its religious education building, Duncanson said. And as with most projects of this type, it came with a complication.

“The big discovery was this cobble pavement at the foot of the staircase,” he said. “We’ve decided to highlight that as an architectural/archaeological feature, but it required extra time to design a plexiglass panel so you can see the original pavement from the 1890s.”

Visitors pay for the never-ending renovation through their purchases from the mission’s gift shop. But while Duncanson is happy to see them, he said it takes some finesse to prevent the mission’s secular side from interfering with its religious purpose.

“It’s difficult when we have tourists coming on a Saturday, and they don’t understand that Saturdays are wedding days, so they don’t have free access to the church during the weddings,” he said. “We try to avoid funerals at times when we schedule school groups. There is a balancing act going on. It wouldn’t be good to have 30 fourth-graders walk into the middle of your funeral.”